This invention relates to a process for obtaining metal values, typically base metals, platinum or gold from a feed material.
U.S. Pat. No. 6,833,021 describes a process for obtaining metal values, typically base metals, platinum or gold from a feed material. In this process, a feed material is milled to a fine size and is leached with a solution comprising lime and/or limestone in the presence of an oxygen containing gas. The reaction is carried out in an open tank and oxygen is introduced via a spear by sparging. The oxygen consumption of the process is high, at 200 to 1000 kg of oxygen per tonne of solids. Heat is added to the tanks and the aim of the process is total sulphide breakdown. The lime consumption of the process is also very high at 100 to 1200 kg of lime and/or limestone per tonne of solids. Furthermore, this process requires a large tank farm for sulphide breakdown and has high capital and operational expenditures.
It is an object of this invention to provide an improved and economical process for obtaining metal values such as base metals, platinum or gold from a feed material.